radio time code clock error

With one admirable exception - lobster thermidor

Sure it does. If you watch the clock, time will seem to go slower. Surely there's a standard for Universal Perceived Time.

I don't want to be late, I simply set my clocks to about 15 minutes ahead. That would be a Leap Quarter Hour.

It also works in the other direction. If I'm expecting a package delivery, it will always be late, the result of time dilation due to the movement of the package. I've also noticed that the faster someone appears to be working towards a deadline, the further behind the project slips, again the result of time dilation and movement.

Mine used to be synchronized to the television show schedule.

"Why are there 24 hours in a day?" The ancient Egyptians apparently were on a decimal system but got derailed by a special interest faction in their standards committee that favored a 12 hr day. At least they tried. I would give the blame/credit to the Babylonians.

The Babylonians got it from some alien astronauts who had six fingers on each hand and six toes on each foot. It must be true. I read it on the internet.

No, it's not 6AM. The Hebrew calendar tries to follow Ye Olde Testament, where God created the heavens and the Earth on the first day, but waited until the 4th day to create the sun. Although "Let there be light" implies that there was light coming from somewhere during the first 3 days, it obviously didn't come from the sun, which first appeared on the 4th day. That also begs the question of how God knew how long to call a day, since the earth didn't have a sun handy with which to tell time. However, if the first 3 days of light came from the sun, it must have taken 4 days for the light to reach Earth, which suggests that God may have done some major remodeling of the solar system before turning on the lights.

Anyway, the Bible says that the first day started with darkness and ended in light, thus making the Hebrew calendar start at sundown, the beginning of darkness.

More drivel: New Years day has changed through history: Jan 1 was the day that Jesus was circumcised:

No visitors from otter space required. Six fingers and/or toes not so rare:

Please note that we all have 11 fingers total. Start counting down on one hand with 10 - 9 - 8 - 7 - 6 and 5 more on the other hand makes

The surest signs of success is pollution. I guess the internet must be successful.

Nice project. Now I think of someone trying to increase its range with a po wer stage and going way too far...

This reminds me of these projects:

I guess something similar could be done to generate a DCF77/WWVB signal.

Oh, I think I didn't explain it right. I meant an additional check for vali d data would be to verify that the received time falls within a reasonable window around the current time. If the clock knows that now is 1:00am +/- 2 minutes it makes no sense to receive 7:42am and take that as valid time.

So the algorithm would be: if there was never a sync before or the user set the time manually => belive whatever time is received, in this case deco ding of several minutes can be done as an extra check). Otherwise (there was a valid sync before and clock time was not changed man ually) check the received time is within a few minutes of clock time. That would help save battery since decoding a single minute would be enough for safe daily sync.

It's amazingly easy to do, but at 60 KHz, the range would be rather limited. It takes some serious power to produce a field strength sufficiently strong to overcome atmospheric noise levels.

Yep. With a 1 baud data rate, it won't take much horsepower to generate the code. You can also buy IRIG-H (used by WWVB etc) time code generators that should work. For example: Just add an AM modulated RF signal generator to produce the 60 KHz, and you're well on your way to becoming the local time lord.

Well, that would work, but there's an easier way. Since one frame is exactly 1 minute long, and there's no way to obtain identical data twice in a row, simply truncating the data to eliminate the minutes and seconds data, would give the clock an hour to obtain to identically truncated receptions. No need for a complex sanity check algorithm. Of course, the receiver would not be turned on for the full hour, but a successful spot check a few minutes after the first successful reception would be sufficient to conserve battery power. I suspect that's the way it's done in the C-Max chips, but I'm not sure.

Diversion: I worked on a failed proposal for an accurate time distribution system that used carrier current repeaters (i.e. HomePlug) to distribute the data. The time source was the GOES satellite system, which belched time sync data on 468.xxx MHz. The satellite data was to be retransmitted at the home or office over power line carrier current frequencies (now Home Plug) to any device that needs accurate time (clocks, computahs, appliances, test equipment, cell sites, SONET, etc). The difference with other radio clock systems is that this one would be continuous, not updated erratically. The GOES signal was strong (+45.5dBm EIRP) that a simple RHCP patch antenna aimed towards the bird was sufficient. I had it mostly working when NASA announced that it was going to pull the plug in 2004. Oh well. Today, it's done with GPSDO driven clocks with much better accuracy.

GOES time receivers.

Maybe so, if they'd lost their minds and were using their computer clocks to aim the DSN, but that's a fantasy. Orbital mechanics bods are all over this timekeeping stuff. It's the stupid software developers who don't know or don't care.

Cheers

Phil Hobbs

It is if it gets out of phase. There's no reason in the world to let it move at all--leap seconds keep civil time in synchrony with mean solar time to within a couple of PPM of a day.

Wanting to get rid of leap seconds is a classical example of a special interest group trying to seize control.

Not that that's unusual, especially these days.

Cheers

Phil Hobbs

Digging deeper. See: It shows the current DSN aiming accuracy at 0.1 nanorads or 15 meters at 1 AU distance. Voyager 1 is currently at 131 AU distance: That grinds out to an accuracy of 2 km meters at a range of 19.6 billion km. Yes, NASA does know the position of Voyager 1 to less than 17 km.

Incidentally, that an angular resolution of: arctan(2/19.6*10^9) = 0.000000006 degrees (or 6*10^-9 deg) A 0.15 degree error, caused by a leap second, would produce a rather astronomical pointing error.

Wow, that's impressive (or I mangled the math again).

Fluke must have thought so. Their 207 receiver has a strip chart recorder. Microdyne used one for decades as part of their time & frequency standard, before replacing it with a GPS derived system for the in house cal lab, and for their Electrical Engineering department. I built a 64 output 10 MHz distribution amp to add the production areas to the system, somewhere around 2000.